The mode of replication of Sindbis virus RNAs is investigated. Also methods are being developed to isolate the envelope protein of the virus. The mode of action of 5-Azacytidine, an anti-leukemia agent in decreasing the infectivity of the viral RNA is studied to determine whether defective virus particles produced in the presence of the drug can be potentially important in the control of viral infections. BIBLIOGRAPHIC REFERENCES: The production of defective Sindbis (SB) virus in baby hamster kidney (BHK-21) cells by Aza-cytidine. M.A. Danello and Tl Sreevalsan. Abstracts of Annual Meeting of American Society for Microbiology. 1976. Characterization of the RNA species of California Encephalitis (CE) virus strain BFS-283. N. Goldman and T. Sreevalsan. Abstracts of Annual Meeting of American Society for Microbiology. 1976.